Hi.
Nice guide!
Some notes:
Never heard the term "axiometric", I belive it should be called isometric this case.
Axonometric illustrations and axonometry in general refers to a drawing made with a Cartesian grid with x, y, z, axises in any direction and scale.
Isometric drawings are such axonometric images, where the axises are in 120? to eachother, and the scales of the axises are 1:1:1.
If the transformation panel is used, 86,60254% for scaling may be quite precise, but not to the max.
(0.48 uses only 3 digits)
Nor that appealing to users not liking math.
Some sort of snapping may do the trick?
For that practical reason, I would also draw a square covering the views, moving them to the bottom, and grouping the objects together
-so in the end there would be 3 object with a square bounding box.
How to scale a square to that (3^0,5)*50% height?
An equilateral triangle would do the trick of the same edge.
Could be snapped it's bounding box to the square's bounding box edge, to make it the same size.
If snapping does not work -converting it to guides and pulling the diagonal guide lines to the square's right corners can be a solution.
Pulling guides from the rulers and changing them direction may also work but it then won't reduce the typing.
Then the horizontal guide (a new one pulled from top ruler in the second case) line needs to be snapped to the diagonal guide lines intersection.
After that, the square can be scaled to the equilateral triangle's bounding box/horizontal guide line, producing the exact scale.
Then, the skewing and rotating can be done much easier by holding Ctrl and moving the handles of the bounding box.
But, if the transformation panel is used, adding a - mark may make it too complicated on a larger project.
Why not to use only one value for each kind of transformation?
-30? skew is equal to mirroring the object (H), applying a 30?skew, and mirroring it back (H).
For the rotate, the cheapo solution would be to click the rotate -90? rotation icon when in object select mode, then apply 30? rotation twice.
(Hmm that may double the inaccuracy, even if not notable.)
In general it is right, but simply using such transformations without a bit of background, can hardly solve cases like drawing a chimney over the gable.
Or drawing cast shadows after.
